//
// Copyright (c) 2013-2022 The SRS Authors
//
// SPDX-License-Identifier: MIT or MulanPSL-2.0
//

#ifndef SRS_KERNEL_FILE_HPP
#define SRS_KERNEL_FILE_HPP

#include <srs_core.hpp>

#include <srs_kernel_io.hpp>

#include <string>

// for srs-librtmp, @see https://github.com/ossrs/srs/issues/213
#ifndef _WIN32
#include <sys/uio.h>
#endif

class SrsFileReader;

/**
 * file writer, to write to file.
 * 写文件
 */
class SrsFileWriter : public ISrsWriteSeeker
{
private:
  	// 文件路径
    std::string path;

	// 文件描述符
    int fd;
public:
    SrsFileWriter();
    virtual ~SrsFileWriter();
public:
    /**
     * open file writer, in truncate mode.
     * @param p a string indicates the path of file to open.
     */
     /**
      * @brief 写文件，使用截断模式
      * @param p 路径
      * @return
      */
      // fixme: (ydc) const std::string &p 是否更好
    virtual srs_error_t open(std::string p);
    /**
     * open file writer, in append mode.
     * @param p a string indicates the path of file to open.
     */
     /**
	* @brief 追加模式打开文件
	* @param p 路径
	* @return srs_error_t
	*/
    virtual srs_error_t open_append(std::string p);
    /**
     * close current writer.
     * @remark user can reopen again.
     */
     // 关闭文件
    virtual void close();
public:
    // 打开文件是否成功
    virtual bool is_open();

	// 文件偏移，做点播业务有需要
    virtual void seek2(int64_t offset);

	// 移动指针到文件末尾，获取文件的大小
    virtual int64_t tellg();
// Interface ISrsWriteSeeker
public:
    virtual srs_error_t write(void* buf, size_t count, ssize_t* pnwrite);
    virtual srs_error_t writev(const iovec* iov, int iovcnt, ssize_t* pnwrite);
    virtual srs_error_t lseek(off_t offset, int whence, off_t* seeked);
};

// The file reader factory.
class ISrsFileReaderFactory
{
public:
    ISrsFileReaderFactory();
    virtual ~ISrsFileReaderFactory();
public:
    virtual SrsFileReader* create_file_reader();
};

/**
 * file reader, to read from file.
 */
class SrsFileReader : public ISrsReadSeeker
{
private:
    std::string path;
    int fd;
public:
    SrsFileReader();
    virtual ~SrsFileReader();
public:
    /**
     * open file reader.
     * @param p a string indicates the path of file to open.
     */
    virtual srs_error_t open(std::string p);
    /**
     * close current reader.
     * @remark user can reopen again.
     */
    virtual void close();
public:
    // TODO: FIXME: extract interface.
    virtual bool is_open();

  	// 重置偏移量为 0
    virtual int64_t tellg();

  	// 偏移量为size
    virtual void skip(int64_t size);

  	//距文件开始处offset个字节大小
    virtual int64_t seek2(int64_t offset);

  	// 移动指针到文件末尾，获取文件的大小
    virtual int64_t filesize();
// Interface ISrsReadSeeker
public:

  	/**
  	 * @brief 读取文件
  	 * @param buf 将要读取的数据域指针
  	 * @param count 需要读取的字节数
  	 * @param pnread 读取完成后，返回本地实际读取到的数据大小
  	 * @return srs_error_t
  	 */
    virtual srs_error_t read(void* buf, size_t count, ssize_t* pnread);


	// 自定义文件的偏移方式
    virtual srs_error_t lseek(off_t offset, int whence, off_t* seeked);
};

// For utest to mock it.
typedef int (*srs_open_t)(const char* path, int oflag, ...);
typedef ssize_t (*srs_write_t)(int fildes, const void* buf, size_t nbyte);
typedef ssize_t (*srs_read_t)(int fildes, void* buf, size_t nbyte);
typedef off_t (*srs_lseek_t)(int fildes, off_t offset, int whence);
typedef int (*srs_close_t)(int fildes);

#endif

